H2S effect

D.C. Chatfield, S.L. Mielke, T.C. Allison, D.G. Truhlar, Quantum dynamical bottlenecks and transition state control of the reaction of D with H2 Effect of varying the total angular momentum, J. Chem. Phys. 112 (2000) 8387. 

ZUEGG AND KRAMER H2 Effect on Pt-Si02 Catalytic Activity... 

The para-H2 effects in the NMR spectra last for the time associated with the re-establishment of the Boltzmann populations defined by the strength of the applied magnetic field and the experimental temperature. Thus, the kinetics associated to the return of the NMR signals to their normal intensities provides information on the relaxation rates of the hydrogenated product as well as of the eventual intermediate(s) formed along the hydrogenation pathway. 

Finally, it has been shown how para-H2 effects in the NMR spectra of hydrogenated products are largely affected by the relaxation processes occurring at intermediate steps represented by hydride derivatives. It is reasonable to foresee that a better control of the hydride relaxation processes occurring at these intermediate steps will allow the detection of even more impressive effects and, as a consequence, novel applications of the PHIP (Para Hydrogen Induced Polarization) experiments. [49]... 

Rh(I) catalysts under H2 effect the reductive cychzation of diynes and enynes [119]. In the example below (1.39), Rh(C0D)20Tf (COD = 1,5-cyclooctadiene) is converted by H2 gas to a Rh hydride, which is thought to undergo oxidative cycliza-tion to produce a rhodacyclopentene intermediate. Cleavage of the Rh-C bonds by reductive elimination to form a vinyl rhodium species, and hydrogenolysis of that intermediate, forms the Rh hydride and the cychzed product. 

In practice, it is found that the presence of sulphur in the atmosphere in the form of H2S effectively suppresses metal dusting. This is thought " to result from the suppression of graphite nucleation by the sulphur, which thereby halts the chain of dusting reactions. 

Figure 11. Dependence on intemucleax distance R of the H2 effective potential surface as function of the electronic coordinates zi and Z2 at constant r and

The results obtained, confirming the possibility of using MCFCs when up to 10 ppm of H2S is present in the feed, have provided suggestions for approaching the interpretation of phenomena for setting up a kinetic equation which also takes account of the H2S effects and allows reliable predictive calculations. 

The HI-receptor is located on many of the same tissues as the H2-receptor, but its activation promotes phosphoinositide hydrolysis, which leads to Ca " mobilization (Garbarg and Schwartz, 1988). H,-mediated events include dilation of pulmonary arteries (Schellenberg et al., 1986), vasopermeability (Northover, 1989 Tomeo etal., 1991), and bronchoconstriction (Maconochie et al., 1979). Counter to H2 effects, Hj activation decreases heart rate and contractile force (Genovese et al.. 

Also, H,-receptor stimulation may amplify H2 effects via intracellular Ca + activation of adenylate cyclase by a calmodulin-calmodulin-binding protein complex in the catalytic subunit of the enzyme (Garbarg and Schwartz, 1988). 

Figure 3-11 covers corrosion tests in boiling 10 and 20% MEA solutions contacted with gas containing both H2S and CO2. The results are quite similar to those of F re 3-10, indicating that the corrosion rate is controlled primarily by the H2S content of the gas and that 5% or more H2S effectively inhibits corrosion regardless of the CO2 content of the gas (up to at least 33% CO2). 

Fig. 2.38 H2 effect on the laminar dame velocity in HYTAN + air mixture [87] interpolation, — ------ — experimental results...

Figure 2.40 H2 effect with HCI solution PSIT-II versus conventional ICPMS (PQ-II). This figure shows spectra for 0.1 % HCI blank solutions recorded with a conventional ICP-MS (top trace) and with the PSIT-I instrument. Note the orders of magnitude reduction in plasma related polyatomics (ArN+, ArO", Ar2 ) and matrix polyatomics (CIO+). Note also the use of H2 results in conversion of Cl" to H2CI. The spectra were each normalized to the Co+ response, which at 10 ng/mL was about the intensity of the ArO" peak in the figure...

The maximum H2S effect was achieved at an H2S level just below that needed to precipitate the CrS phase on the alloy surface." ... 

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